Comments

This is a note to let you know that I have just added a patch titled
ext4: fix unjournaled inode bitmap modification
to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Herton
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From 56f704f089db01b6eee88810c0c0506276bf7e35 Mon Sep 17 00:00:00 2001
From: Eric Sandeen <sandeen@redhat.com>
Date: Sun, 28 Oct 2012 22:24:57 -0400
Subject: [PATCH] ext4: fix unjournaled inode bitmap modification
X-Extended-Stable: 3.5
commit ffb5387e85d528fb6d0d924abfa3fbf0fc484071 upstream.
commit 119c0d4460b001e44b41dcf73dc6ee794b98bd31 changed
ext4_new_inode() such that the inode bitmap was being modified
outside a transaction, which could lead to corruption, and was
discovered when journal_checksum found a bad checksum in the
journal during log replay.
Nix ran into this when using the journal_async_commit mount
option, which enables journal checksumming. The ensuing
journal replay failures due to the bad checksums led to
filesystem corruption reported as the now infamous
"Apparent serious progressive ext4 data corruption bug"
[ Changed by tytso to only call ext4_journal_get_write_access() only
when we're fairly certain that we're going to allocate the inode. ]
I've tested this by mounting with journal_checksum and
running fsstress then dropping power; I've also tested by
hacking DM to create snapshots w/o first quiescing, which
allows me to test journal replay repeatedly w/o actually
power-cycling the box. Without the patch I hit a journal
checksum error every time. With this fix it survives
many iterations.
Reported-by: Nix <nix@esperi.org.uk>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
fs/ext4/ialloc.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
--
1.7.9.5